The need for an apparatus capable of diffusely illuminating a variety of objects and subjects is well known. See for instance U.S. Pat. Nos. 4,335,421 and 4,669,031, respectively disclosing apparati for illuminating x-ray negatives from behind or photographic subjects directly, and discussing other uses such as illuminated tracing tables. All of these applications require either a diffusely illuminated surface (for lighting from behind) or a surface which radiates a diffuse light for direct illumination. A number of apparati have been proposed to suit these applications. See for instance the U.S. patent numbers reference above. In the photographic industry, particularly in that branch of the industry dealing with the photography of large subjects for advertising or editorial purposes such as for display quality photographs of new automobiles, an apparatus generally referred to as a banklight or softlight is employed. These banklights are generally large compared to other lighting fixtures, as they are generally in the size range of ten feet wide by thirty feet long, although both larger and smaller versions are also known. Conventional banklights are known to produce an approximation of diffuse light, but they are large, cumbersome, and time consuming in set-up and takedown, and therefore very expensive to operate. One such conventional banklight apparatus in shown generally in cross-section in FIG. 11. The reflective surface of such a banklight may be a parabolic, ellipsoidal, or circular curve, and the light source schematically shown is typically a line of photo flashtubes or quartz halogen lamps. The diffusing fabric attempts to make up for the nonuniformity of the reflected light rays coming from the reflecting surface, but is only partially successful in doing so.
None of the known apparati are capable of quick and easy set-up and take down and none of them are well adapted for banklight configurations as large as eighteen by forty-eight feet, or even larger. In addition none of the known systems employ multiple lines of light sources, each line independently controlled so as to produce, when desired, a gradual and uniform variation of light intensity across the surface of the light fixture, and no known apparatus employs a system of reflecting and diffusing panels to achieve, as desired, either a virtually uniform diffusion of light, or a controlled gradation of diffuse light, while at the same time achieving a very low ratio of thickness of the apparatus to its width.